1. Field of the Invention
The present invention relates to a connector having a locking arm.
2. Description of the Related Art
A connector with a locking arm is disclosed in Japanese Patent Application Laid-Open No. 1-112577. This prior art connector includes a connector housing, and the locking arm is formed integrally with an outer surface of the connector housing. The locking arm includes a base part erected from the outer surface of the connector housing. An arm part cantilevered is from the base part and extends along the outer surface of the connector housing. A locking projection is formed on the outer surface of the arm part, which is the surface facing away from the outer surface of the connector housing. The connector and a mating connector are connectable with each other. During this connection, the locking projection interferes with the hood of the mating connector. As a result, the locking arm flexes elastically toward the outer surface of the connector housing. When both connectors are placed in the normal fit-in state, the locking arm is restored elastically to its original state, and the locking projection is locked in the locking hole of the hood. As a result, both connectors are locked to each other in the normal fit-in state.
Prior art connectors have a connector housing that accommodates metal terminal fittings. The metal terminal fittings are fixed to ends of electric wires, and several such wire/connector housing assemblies are combined with each other to produce a wire harness subassembly. Wire harness subassemblies are packed in a shipping case for transport by piling them up one upon another.
The prior art connector with a locking arm also includes a flexure space between the locking arm and the outer surface of the connector housing. The locking arm is cantilevered and extended over the connector housing. Thus, there is a possibility that a foreign matter may penetrate into the flexure space between the locking arm and the outer surface of the connector housing.
The prior art wire harness subassemblies are taken out from the shipping case one by one in a place where they are assembled with other wires and connector housings to produce the wire harness. However, an electric wire of another wire harness subassembly that is still in the shipping case may penetrate into the flexure space and may be caught by the locking arm. If the wire harness subassembly is taken out forcibly from the shipping case in this state, the locking arm of the connector caught by the electric wire is subjected to a force for displacing the locking arm away from the outer surface of the connector housing, with the locking arm tilting on the base part acting as the supporting point.
In this event, there is a possibility that the locking arm of the conventional connector may be broken at its base part even though the displacement amount of the locking arm is not very great.
The present invention has been made in view of the above-described situation, and an object of the present invention is to prevent breakage of a locking arm displaced away from a connector housing.
The present invention is directed to a connector having a connector housing and a locking arm formed integrally with an outer surface of the connector housing. The locking arm includes a base part erected from the outer surface of the connector housing. An arm part is cantilevered from the base part and extends almost parallel with the outer surface of the connector housing. Thus a flexure space is defined between the outer surface of the connector housing and an inner surface of the arm part. The flexure space enables the arm part to flex elastically when the connector and a mating connector are locked to each other. In this construction, a groove is formed on the base part and the arm part, such that the groove formed on the base part extends along a direction in which the base part is erected and the groove formed on the arm part extends along a direction in which the arm part is extended. A thickness between a bottom surface of a groove of the base part and a surface thereof opposite to the bottom surface is almost equal to or larger than a thickness of the arm part.
Preferably, the groove of the base part is formed on a surface that receives a compression load when the locking arm is displaced in a direction away from an outer surface of the connector housing.
Preferably, a substantially cylindrically generated arc-shaped surface is defined on a surface of the base part that is continuous both with an inner surface of the arm part and with the outer surface of the connector housing.
As noted above, the prior art locking arm often is broken at its base part when the locking arm tilts away from the outer surface of the connector housing. It is believed that this breakage may occur because the base part has a great increase in the rate of strain relative to change in the tilting angle of the rear end portion of the arm part because the locking arm tilts from the connector housing, with the base part acting as the supporting point of the tilting motion of the locking arm.
According to the present invention, the groove is formed on both the base part and the arm part, and the thickness between a bottom surface of the groove of the base part and the rear surface thereof is almost equal to or larger than the thickness of the arm part. Thus, a portion at both sides of the groove in the base part projects in the shape of a rib. Accordingly, the base part is less flexible than the arm part and thus increase of the strain of the base part is suppressed. On the other hand, the formation of the groove allows the arm part to be more flexible than the base part. Consequently, the deformation of the arm part relaxes the tilting force applied to the base part.
When a tensile load is applied to the rib-shaped portion at both sides of the groove, a stress concentrates on one point and thus the outer surface of the rib-shaped portion is liable to crack and break. But, according to the first embodiment, a compression load is applied to the rib-shaped portion. Consequently, the stress is applied widely to the locking arm. Therefore, there is no fear that the locking arm is broken.
The rear surface of the base part that is continuous with the inner surface of the arm part and with the outer surface of the connector housing defines a generally cylindrical arc-shaped surface. Thus, the rear surface of the base part has a larger radius of curvature than a surface formed by a combination of a curved surface and a flat surface. Thus, a concentration of the stress on the rear surface of the base part is prevented, which allows the base part to have a higher breakage prevention function.